Organic light-emitting display apparatus and method of manufacturing the same

ABSTRACT

An organic light-emitting display apparatus including: a substrate; a plurality of pixels that are formed on the substrate and each have a light emission area from which visible rays are emitted and a transmission area through which external light is transmitted; a pixel circuit portion disposed in each light emission area of the plurality of pixels; a first electrode that is disposed in each light emission area and is electrically connected to the pixel circuit portion; an intermediate layer that is formed on the first electrode and includes an organic emissive layer; a second electrode formed on the intermediate layer; and a capping layer that is disposed on the second electrode and includes a first capping layer corresponding to the light emission area and a second capping layer corresponding to the transmission area. Accordingly, electrical characteristics and image quality of the organic light-emitting display apparatus may be improved.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application is a divisional application of U.S. patent applicationSer. No. 13/443,820, filed on Apr. 10, 2012, which claims priority toand the benefit of Korean Patent Application No. 10-2011-0141719, filedon Dec. 23, 2011, in the Korean Intellectual Property Office, thedisclosures of which are incorporated herein in their entirety byreference.

BACKGROUND 1. Field

The following description relates to an organic light-emitting displayapparatus and a method of manufacturing the same.

2. Description of the Related Art

Flat panel display apparatuses are thin and portable displayapparatuses. Among the flat panel display apparatuses, organiclight-emitting display apparatuses are self-emissive display apparatuseswhich have wide viewing angles, excellent contrast, and high responsespeeds. Thus, the organic light-emitting display apparatuses are beingrecognized (noticed) as next-generation display apparatuses.

An organic light-emitting display apparatus includes an intermediatelayer, a first electrode, and a second electrode. The intermediate layerincludes an organic emissive layer, and when a voltage is applied to thefirst and second electrodes, the organic emissive layer produces visiblerays.

Here, due to a sealing member disposed on the second electrode or otherimpurities, the second electrode may be polluted or damaged.

Thus, it is difficult to improve image quality and electricalcharacteristics of the organic light-emitting display apparatus.

SUMMARY

Aspects of embodiments of the present invention are directed toward anorganic light-emitting display apparatus having improved electricalcharacteristics and/or image quality, and a method of manufacturing theorganic light-emitting display apparatus.

According to an embodiment of the present invention, there is providedan organic light-emitting display apparatus including: a substrate; aplurality of pixels that are formed on the substrate and each have alight emission area from which visible rays are emitted and atransmission area through which external light is transmitted; a pixelcircuit portion disposed in each light emission area of the plurality ofpixels; a first electrode that is disposed in each light emission areaand is electrically connected to the pixel circuit portion; anintermediate layer that is formed on the first electrode and includes anorganic emissive layer; a second electrode formed on the intermediatelayer; and a capping layer that is disposed on the second electrode andincludes a first capping layer corresponding to the light emission areaand a second capping layer corresponding to the transmission area.

The capping layer may be light-transmissive.

The first capping layer and the second capping layer may have differentthicknesses.

The second capping layer may be thinner than the first capping layer.

The second capping layer may include a plurality of sub-capping layers.

The first capping layer and the second capping layer may be separatedfrom each other in at least a first direction and a second directionperpendicular to the first direction (or in at least one area).

The first capping layer and the second capping layer may include thesame material.

The first capping layer and the second capping layer may includedifferent materials.

The capping layer may comprise 8-quinolinolato lithium (Liq),N,N-diphenyl-N,N-bis(9-phenyl-9H-carbazol-3-yl)biphenyl-4,4′-diamine,N(diphenyl-4-yl)9,9-dimethyl-N-(4(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluorene-2-amine,or2-(4-(9,10-di(naphthalene-2-yl)anthracene-2-yl)phenyl)-1-phenyl-1H-benzo-[D]imidazole.

The second electrode may be light-transmissive.

The capping layer may be formed on the second electrode in a first areaand has a first edge, the organic light-emitting display apparatus mayfurther include a third electrode that is formed on the second electrodein a second area other than the first area (or in an entire top surfacearea of the second electrode except the first area) and has a secondedge, and a lateral surface of the first edge of the capping layer and alateral surface of the second edge of the third electrode contact eachother.

The third electrode may be is thicker than the second electrode.

An adhesive force between the third electrode and the capping layer maybe weaker than an adhesive force between the third electrode and thesecond electrode.

The third electrode may comprise magnesium (Mg).

All edges of the capping layer and an edge of the third electrode maycontact each other.

According to another embodiment of the present invention, there isprovided a method of manufacturing an organic light-emitting displayapparatus including a plurality of pixels each including a lightemission area from which visible rays are emitted and a transmissionarea through which external light is transmitted, the method comprising:forming a plurality of pixel circuit portions on a substrate torespectively correspond to the plurality of pixels; forming a firstelectrode that is disposed in a light emission area of each of theplurality of pixels and is electrically connected to a corresponding oneof the pixel circuit portions; forming an intermediate layer, includingan organic emissive layer, on the first electrode; forming a secondelectrode on the intermediate layer; and forming a capping layer on thesecond electrode, wherein the capping layer comprises a first cappinglayer corresponding to the light emission area and a second cappinglayer corresponding to the transmission area.

The first capping layer and the second capping layer may be formedseparately.

The first capping layer and the second capping layer may be formed usinga mask.

The capping layer may be formed in a first area on the second electrodeand have a first edge, the method may further include forming a thirdelectrode that is formed in a second area other than the first area onthe second electrode and has a second edge, and a lateral surface of thefirst edge of the capping layer and a lateral surface of the second edgeof the third electrode are formed to contact each other.

The forming of the third electrode may comprise patterning the thirdelectrode by using a pattern of the capping layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent by describing in detail exemplary embodimentsthereof with reference to the attached drawings in which:

FIG. 1 is a cross-sectional view illustrating an organic light-emittingdisplay apparatus according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view illustrating an organic light-emittingdisplay apparatus according to another embodiment of the presentinvention;

FIG. 3 is a plan view illustrating an organic light-emitting unit ofFIG. 1;

FIG. 4 is a cross-sectional view illustrating a pixel of FIG. 3;

FIG. 5 is a detailed plan view of a capping layer of the organiclight-emitting unit of FIG. 1, according to an embodiment of the presentinvention;

FIG. 6 is a plan view of a capping layer of the organic light-emittingunit, according to another embodiment of the present invention;

FIG. 7 is a plan view of a capping layer of the organic light-emittingunit, according to another embodiment of the present invention;

FIG. 8 is a plan view illustrating an organic light-emitting unitaccording to another embodiment of the present invention; and

FIG. 9 is a graph showing light transmittance according to thickness ofa capping layer.

DETAILED DESCRIPTION

The present invention will now be described more fully with reference tothe accompanying drawings, in which exemplary embodiments of theinvention are shown. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.Expressions such as “at least one of,” when preceding a list ofelements, modify the entire list of elements and do not modify theindividual elements of the list.

FIG. 1 is a cross-sectional view illustrating an organic light-emittingdisplay apparatus 2 according to an embodiment of the present invention.

Referring to FIG. 1, the organic light-emitting display apparatus 2includes a substrate 1, an organic light-emitting unit 21 formed on thesubstrate 1, and an encapsulation substrate 23 that encapsulates theorganic light-emitting unit 21.

The encapsulation substrate 23 includes a transparent material so thatvisible rays generated by the organic light-emitting unit 21 maytransmit therethrough, and prevents (blocks) penetration of external airand water into the organic light-emitting unit 21.

The substrate 1 and the encapsulation substrate 23 are coupled using asealing member 24 so that space 25 between the substrate 1 and theencapsulation substrate 23 is encapsulated. A moisture absorbingmaterial or filler may be included in the space 25.

FIG. 2 is a cross-sectional view illustrating an organic light-emittingdisplay apparatus 2 according to another embodiment of the presentinvention. Instead of the encapsulation substrate 23 of FIG. 1, a thinencapsulation layer 26 may be formed on an organic light-emitting unit21, as illustrated in FIG. 2, to protect the organic light-emitting unit21 from external air. The encapsulation layer 26 may have a structure inwhich an inorganic layer formed of silicon oxide or silicon nitride orthe like and an organic layer formed of epoxy or polyimide or the likeare alternately stacked, but is not limited thereto. Any encapsulationstructure that is a thin transparent layer may be used.

FIG. 3 is a plan view illustrating the organic light-emitting unit 21 ofFIG. 1, and FIG. 4 is a cross-sectional view illustrating a pixel ofFIG. 3.

Referring to FIGS. 3 and 4, the organic light-emitting unit 21 isdivided into a transmission area TA through which external light istransmitted and a plurality of light emission areas PA that are adjacentto the transmission area TA.

As illustrated in FIG. 3, in each of the light emission areas PA, apixel circuit portion PC is included and a plurality of conductivelines, such as a scan line S, a data line D, and a Vdd line V, areelectrically connected to the pixel circuit portion PC. Although notillustrated in FIG. 3, other conductive lines besides the scan line S,the data line D, and the Vdd line V may be included according to theconfiguration of the pixel circuit portion PC.

In FIG. 3, the pixel circuit portion PC may include at least one thinfilm transistor connected to the scan line S and the data line D, a thinfilm transistor connected to the Vdd line C, or the like, and acapacitor. The thin film transistors of the pixel circuit portion PC mayinclude a switching transistor and a driving transistor. Also, the thinfilm transistors of the pixel circuit portion PC may be either p-type orn-type transistor, and the number of capacitors of the pixel circuitportion PC may vary.

Referring to FIG. 3, the scan line S overlaps with a first electrode221. However, the embodiment of the present invention is not limitedthereto, and at least one of the plurality of conductive lines, such asthe scan line S, the data line D, and the Vdd line V, may be disposed tooverlap with the first electrode 221, and also, according tocircumstances, all of the plurality of conductive lines, such as thescan line S, the data line D, and the Vdd line V, may overlap with thefirst electrode 221 or may be disposed next to the first electrode 221.

Referring to FIG. 4, a buffer layer 211 is formed on a substrate 1, anda thin film transistor TR1 is formed on the buffer layer 211.

While only one thin film transistor TR1 is illustrated in FIG. 4, theembodiment of the present invention is not limited thereto, as describedabove, and a plurality of transistors and at least one capacitor may beincluded in each pixel.

A semiconductor active layer 212 is formed on the buffer layer 211.

The buffer layer 211 prevents penetration of impurities into thesubstrate 1 and provides a planar surface over the substrate 1. Thebuffer layer 211 may be formed of any materials that may perform thesefunctions. For example, the buffer layer 211 may include an inorganicmaterial, such as silicon oxide, silicon nitride, silicon oxynitride,aluminum oxide, aluminum nitride, titanium oxide, or titanium nitride,or an organic material such as polyimide, polyester, or acryl, and mayalso be formed of a stack structure of such materials. However, thebuffer layer 211 is not an essential component and may be omitted whensuitable.

The semiconductor active layer 212 may be formed of polycrystallinesilicon, but is not limited thereto, and may be formed of an oxidesemiconductor. For example, the semiconductor active layer 212 may be aG-I—Z—O layer [(In₂O₃)a(Ga₂O₃)b(ZnO)c layer](where a, b, and crespectively satisfy a≥0, b≥0, c>0).

A gate insulating layer 213 is formed on the buffer layer 211 to coverthe semiconductor active layer 212, and a gate electrode 214 is formedon the gate insulating layer 213.

An interlayer insulating layer 215 is formed to cover the gate electrode214. A source electrode 216 and a drain electrode 217 are formed on theinterlayer insulating layer 215 to be electrically connected to thesemiconductor active layer 212.

The thin film transistor TR1 is not limited to the above-describedstructure, and other thin film transistor structures may be applied. Forexample, the thin film transistor TR1 described above has a top gatestructure, but the thin film transistor TR1 may also have a bottom gatestructure in which the gate electrode 214 is disposed below thesemiconductor active layer 212. Also, other thin film transistorstructures may be used.

A passivation layer 218 is formed on the interlayer insulating layer 215to cover the pixel circuit portion PC including the thin film transistorTR1. The passivation layer 218 may be a single insulating layer or aplurality of insulating layers having a planarized upper surface. Thepassivation layer 218 may be formed of an inorganic and/or organicmaterial.

A first electrode 221 that is electrically connected to the thin filmtransistor TR1 is formed on the passivation layer 218. The firstelectrode 221 is formed to be in an independent island form in eachpixel.

A pixel-defining layer 219 is formed on the passivation layer 218 tocover an edge of the first electrode 221. An opening 219 a is formed inthe pixel-defining layer 219 to expose a central portion of the firstelectrode 221 except the edge thereof.

An intermediate layer 220, including an organic emissive layer, isformed on the exposed central portion of the first electrode 221, and asecond electrode 222 is formed on the intermediate layer 220 to coverthe intermediate layer 220, thereby completing the manufacture of anorganic light-emitting device EL.

The intermediate layer 220 may include a low-molecule or polymer organiclayer. When the intermediate layer 220 is formed of a low-moleculeorganic layer, the intermediate layer 220 may include a hole injectionlayer (HIL), a hole transport layer (HTL), an organic emissive layer, anelectron transport layer (ETL), an electron injection layer (EIL), orthe like. The organic emissive layer is formed in each of red, green,and blue pixels, and the HIL, the HTL, the ETL, and the EIL are commonlayers that are commonly applied to the red, green, and blue pixels.

The HIL may be formed of a phthalocyanine compound such as a copperphthalocyanine or a starburst type amine such as TCTA, m-MTDATA,m-MTDAPB or the like.

The HTL may be formed of, for example,NN-bis(3-methylphenyl)-N,N′-diphenyl-[1,1-biphenyl]-4,4′-diamine(TPD),N,N′-di(naphthalene-1-il-N,N′-diphenyl benzidine(α-NPD), or the like.

The EIL may be formed of, for example, LiF, NaCl, CsF, Li₂O, BaO, orLiq.

The ETL may be formed using Alq3.

The organic emissive layer may include a host material and a dopantmaterial.

The host material of the organic emissive layer may be, for example,tris(8-hydroxy-quinolinato)aluminum (Alq3),9,10-di(naphti-2-yl)anthracene (AND),3-Tert-butyl-9,10-di(naphthi-2-yl)anthracene (TBADN),4,4′-bis(2,2-diphenyl-ethene-1-yl)-4,4′-dimethylphenyl (DPVBi),4,4′-bisBis(2,2-diphenyl-ethene-1-yl)-4,4′-dimethylphenyl (p-DMDPVBi),Tert(9,9-diarylfluorene)s (TDAF),2-(9,9′-spirobifluorene-2-yl)-9,9′-spirobifluorene (BSDF),2,7-bis(9,9′-spirobifluorene-2-yl)-9,9′-spirobifluorene (TSDF),bis(9,9-diarylfluorene)s (BDAF),4,4′-bis(2,2-diphenyl-ethene-1-yl)-4,4′-di-(tert-butyl)phenyl(p-TDPVBi), 1,3-bis(carbazole-9-yl)benzene (mCP),1,3,5-tris(carbazole-9-yl)benzene (tCP),4,4′,4″-tris(carbazole-9-yl)triphenylamine (TcTa),4,4′-bis(carbazole-9-yl)biphenyl (CBP),4,4′-bisBis(9-carbazolyl)-2,2′-dimethyl-biphenyl (CBDP),4,4′-bis(carbazole-9-yl)-9,9-dimethyl-fluorene (DMFL-CBP),4,4′-bis(carbazole-9-yl)-9,9-bisbis(9-phenyl-9H-carbazole)fluorene(FL-4CBP), 4,4′-bis(carbazole-9-yl)-9,9-di-tolyl-fluorene (DPFL-CBP), or9,9-bis(9-phenyl-9H-carbazole)fluorene (FL-2CBP).

The dopant material of the organic emissive layer may be, for example,4,4′-bis[4-(di-p-tolylamino)styryl]biphenyl (DPAVBi),9,10-di(naph-2-tyl)anthracene (ADN), or3-tert-butyl-9,10-di(naph-2-tyl)anthracene (TBADN).

The first electrode 221 may function as an anode, and the secondelectrode 222 may function as a cathode, but the polarities of the firstand second electrodes 221 and 222 may be exchanged.

When the first electrode 221 functions as an anode, the first electrode221 may include a material having a high work function, such as ITO,IZO, ZnO, or In₂O₃. Also, according to purpose or design, the firstelectrode 221 may further include a reflection layer formed of, forexample, Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Yb, or Ca.

When the second electrode 222 functions as a cathode electrode, thesecond electrode 222 may be formed of a metal, such as Ag, Mg, Al, Pt,Pd, Au, Ni, Nd, Ir, Cr, Li, or Ca. When the organic light-emittingdisplay apparatus 2 is a top emissive type display apparatus in which animage is formed away from the substrate 1, light needs to be transmittedthrough the second electrode 222. To this end, the second electrode 222may include a transparent metal oxide, such as ITO, IZO, ZnO, or In₂O₃.Alternatively, the second electrode 222 may be formed as a thin film byusing Al, Ag, and/or Mg. For example, the second electrode 222 may beformed in a single-layer structure or a stack structure including Mg:Agand/or Ag. Unlike the first electrode 221, the second electrode 222 isformed such that a common voltage is applied to each of all pixelsthereof, and to this end, the second electrode 222 is formed as a commonelectrode to all pixels and is not formed of a plurality of patterns tocorrespond to pixels. Alternatively, the second electrode 222, which isthe common electrode, may also be patterned into a mesh form, from whichportions except those corresponding to a light emission area areremoved.

When the second electrode 222 is formed as a common electrode, surfaceresistance of the second electrode 222 is increased, thereby causingvoltage drop (IR drop). According to the current embodiment of thepresent invention, to solve this issue, a third electrode 223 that iselectrically connected to the second electrode 222 may be furtherincluded.

In addition, an upper surface of the second electrode 222 may be damagedby the encapsulation substrate 23 of FIG. 1. Moreover, when forming theencapsulation layer 26 as illustrated in FIG. 2, the second electrode222 is likely to be damaged when forming the encapsulation layer 26.Also, the second electrode 222 is likely to be damaged by external airor impurities. According to the current embodiment of the presentinvention, a capping layer 230 may be formed on the second electrode222.

The capping layer 230 includes a first capping layer 231 and a secondcapping layer 232. The first capping layer 231 may be formed tocorrespond to the light emission area PA, and the second capping layer232 may be formed to correspond to the transmission area TA. Also, thefirst capping layer 231 and the second capping layer 232 may be formedseparately. In more detail, the thicknesses of the first capping layer231 and the second capping layer 232 may be different, and inparticular, a thickness of the second capping layer 232 may be less thanthat of the first capping layer 231.

The capping layer 230 is formed on the second electrode 222 in a firstarea R1 and has a first edge 230 a.

The third electrode 223 is formed on the second electrode 222 in asecond area R2 and has a second edge 223 a. The third electrode 223 isadjacent and horizontal to the capping layer 230.

The first area R1 corresponds to the light emission area PA and thetransmission area TA in at least one pixel, and an edge of the firstarea R1 is the first edge 230 a of the capping layer 230. The secondarea R2 corresponds to a portion of the second electrode 222 other than(or except) the first area R1, the third electrode 223 is formed overthe entire second area R2, and an edge of the second area R2 is thesecond edge 223 a of the third electrode 223. The second area R2 is anarea except at least the light emission area PA.

A lateral surface of the first edge 230 a of the capping layer 230 and alateral surface of the second edge 223 a of the third electrode 223contact each other.

The third electrode 223 may preferably be thicker than the secondelectrode 222 to reduce surface resistance of the second electrode 222.

The capping layer 230 may preferably be light-transmissive. Inparticular, in the transmission area TA, desirably, visible raystransmit through the second capping layer 232 as much as possiblewithout losing optical characteristics, and thus, transmittance of thesecond capping layer 232 may preferably be high.

Also, in the light emission area PA, desirably, visible rays generatedby the intermediate layer 220 should transmit through the first cappinglayer 231 without losing optical characteristics. That is, the firstcapping layer 231 may preferably be formed such that visible raysgenerated by the intermediate layer 220 transmit through the firstcapping layer 231 and image quality, such as luminance, contrast, colorconversion, or the like, are considered at the same time.

For example, the second capping layer 232 may be thinner than the firstcapping layer 231 to improve transparency of the transmission area TAand image quality of the light emission area PA.

The capping layer 230 may be formed as a thin layer that is thinner thanthe third electrode 223, but is not limited thereto.

According to an embodiment of the present invention, an adhesive forcebetween the third electrode 223 and the capping layer 230 is set to beweaker than an adhesive force between the third electrode 223 and thesecond electrode 222.

To this end, the capping layer 230 may be formed of a material including8-quinolinolato lithium (Liq),N,N-diphenyl-N,N-bis(9-phenyl-9H-carbazol-3-yl)biphenyl-4,4′-diamine,N(diphenyl-4-yl)9,9-dimethyl-N-(4(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluorene-2-amine,or2-(4-(9,10-di(naphthalene-2-yl)anthracene-2-yl)phenyl)-1-phenyl-1H-benzo-[D]imidazole.

The first capping layer 231 and the second capping layer 232 may beformed using the same material for simplicity of manufacture, but theembodiment of the present invention is not limited thereto, and thefirst capping layer 231 and the second capping layer 232 may alsoinclude different materials.

Also, the third electrode 223 may be formed of magnesium (Mg).

Magnesium (Mg) of the third electrode 223 is a metal, and thus, has agood adhesive property with respect to the second electrode 222.However, Mg is not easily adhered to the material of the capping layer230. Thus, the third electrode 223 may be easily patterned by using theadhesive force between the third electrode 223 and the capping layer230.

As described above, the third electrode 223 is patterned so that thethird electrode 223 is formed only in the second area R2. However, afterforming the intermediate layer 220 of the organic light-emitting deviceEL, the third electrode 223 may not be patterned using a wet processsuch as a photolithography method which is frequently used as apatterning method of a typical metal layer, because when waterand/oxygen penetrates into the intermediate layer 220 in the wetprocess, the lifespan (lifetime) of the organic light-emitting device ELis abruptly decreased.

Thus, it is difficult to pattern the third electrode 223 in actuality.

According to the current embodiment of the present invention, the thirdelectrode 223 may be simply patterned using an adhesive force betweenthe third electrode 223 and the capping layer 230. Hereinafter, a methodof manufacturing the capping layer 230, according to an embodiment ofthe present invention, will be described in more detail.

First, the manufacturing method is the same until forming the secondelectrode 222, and then a mask is used to form the capping layer 230.The capping layer 230 may be formed of an organic material describedabove, and thus, may be formed using a thermal evaporation method usinga mask. An opening is formed in the mask to correspond to a pattern ofthe capping layer 230.

Here, the first capping layer 231 and the second capping layer 232 areformed separately. That is, the first capping layer 231 is formed usinga mask having an opening corresponding to the first capping layer 231,and then the second capping layer 232 is formed using a mask having anopening corresponding to the second capping layer 232. Referring to FIG.5, the first capping layer 231 and the second capping layer 232 havedifferent sizes, and in this case, the first capping layer 231 and thesecond capping layer 232 may be formed using different masks.

However, the embodiment of the present invention is not limited thereto,and when the first capping layer 231 and the second capping layer 232are to be formed similarly, the first capping layer 231 may be formedfirst using a mask, and then the mask may be used to form the secondcapping layer 232.

Alternatively, the first capping layer 231 may be formed after formingthe second capping layer 232.

Then, an open mask having an overall opening corresponding to all pixelsis used to form the third electrode 223 using a material for forming thethird electrode 223. In this case, the material for forming the thirdelectrode 223 has poor adhesive force with respect to the capping layer230, and thus, is not formed on the capping layer 230, and is formedonly on the second electrode 222, which has a relatively good adhesiveforce.

Accordingly, the third electrode 223 may be spontaneously (naturally)patterned at a desired position without an additional patterningoperation such as a photolithography method.

FIG. 5 is a detailed plan view of the capping layer 230 of the organiclight-emitting unit 21 of FIG. 1, according to an embodiment of thepresent invention. As illustrated in FIG. 5, the capping layer 230 maybe formed to be in an island form in each pixel P. The first cappinglayer 231 and the second capping layer 232 are formed separately, andthus, may be spaced apart from each other. However, the embodiment ofthe present invention is not limited thereto, and the first cappinglayer 231 and the second capping layer 232 may be formed adjacent toeach other or may overlap by a portion, particularly, edge portionsthereof.

The third electrode 223 is arranged as a lattice pattern between pixelsP.

FIG. 6 is a plan view of a capping layer 230 of the organiclight-emitting unit 21 according to another embodiment of the presentinvention. In FIG. 6, as an example of the capping layer 230 of theorganic light-emitting unit 21 of FIG. 1, the second capping layer 232of the capping layer 230 may include sub-capping layers 232A and 232B.In this case, when forming the capping layer 230, the first cappinglayer 231, the sub-capping layer 232A, and the sub-capping layer 232Bmay be sequentially formed. That is, the capping layer 230 may be formedby three operations. The capping layer 230 may also be formed using asingle mask. A boundary between the sub-capping layer 232A and thesecond sub-capping layer 232B may be in the transmission area.

Also, the sub-capping layers 232A and 232B of the second capping layer232 include the above-described materials for forming the capping layer230 and may be formed of the same material. However, the embodiment ofthe present invention is not limited thereto, and the sub-capping layers232A and 232B of the second capping layer 232 may also be formed usingdifferent materials.

Also, according to another embodiment of the present invention, thecapping layer 230 of the organic light-emitting unit 21 of FIG. 1 may beformed to be in an island form in a plurality of pixels P as illustratedin FIG. 7. In this case, the third electrode 223 is arranged as alattice pattern that passes by spaces between the plurality of pixels P.Although not illustrated in FIG. 7, the second capping layer 232 of thecapping layer 230 may also include a plurality of sub-capping layers, asillustrated in FIG. 6.

Although not illustrated in the drawings, when forming the thirdelectrode 223, a material for forming the third electrode 223 may beformed not only in an area except the capping layer 230, but also as athin layer that is thinner than the third electrode 223 formed in thearea except the capping layer 230, since the material for forming thethird electrode 223 has poor adhesive force with respect to the cappinglayer 230. That is, the material should theoretically not form as alayer on the capping layer 230. In addition, even if the material isformed as a layer only on the second electrode 222 having a relativelygood adhesive force, the material for forming the third electrode 223 isdeposited without using an additional patterning mask but using an openmask. Consequently, a very thin layer may be formed on the capping layer230 in a physically unstable state.

However, since the material for forming the third electrode 223, whichmay be formed on the capping layer 230, is very thin, the material doesnot have a great influence on the luminance of the organiclight-emitting device EL.

According to the current embodiment of the present invention, as thelight emission area PA and the transmission area TA are separate, whenobserving the outside through the transmission area TA, distortion ofexternal images generated due to diffusion of external light related topatterns of devices in the pixel circuit portion PC may be reduced orprevented.

The light emission area PA and the transmission area TA are formed suchthat a ratio of a surface area of the transmission area TA with respectto the total surface area of the light emission area PA and thetransmission area TA is in a range from about 5% to about 90%.

In one embodiment, if the ratio of the surface area of the transmissionarea TA with respect to the total surface area of the light emissionarea PA and the transmission area TA is less than 5%, the amount oflight that is transmitted through the transmission area TA may be small,and thus, a viewer may have difficulty viewing an object or an image onthe opposite side of the organic light-emitting display apparatus 2.That is, the organic light-emitting unit 21 may not be regarded astransparent. However, even if the ratio of the surface area of thetransmission area TA with respect to the total surface area of the lightemission area PA and the transmission area TA is about 5%, if anintensity of external light is high, a user may sufficiently recognizean object or an image disposed on the opposite side, through the organiclight-emitting display apparatus 2, and thus, the user may regard theorganic light-emitting unit 21 as a transparent display unit. Inaddition, when the thin film transistor of the pixel circuit portion PCis formed as a transparent thin film transistor, such as an oxidesemiconductor, and an organic light-emitting device is also formed of atransparent device, the effect of the organic light-emitting displayapparatus 2 as a transparent display apparatus may be enhanced.

In another embodiment, if the ratio of the surface area of thetransmission area TA with respect to the total surface area of the lightemission area PA and the transmission area TA is greater than 90%, pixelintegration of the organic light-emitting unit 21 is too low and imagesmay not be stably formed through light emission of the light emissionarea PA. That is, the smaller the surface area of the light emissionarea PA, the higher the need of luminance of light emitted from theintermediate layer 220. Thus, if an organic light-emitting device isoperated in a high luminance mode, the lifespan (lifetime) of theorganic light-emitting display apparatus 2 is abruptly decreased.

Thus, the ratio of the surface area of the transmission area TA withrespect to the total surface area of the light emission area PA and thetransmission area TA may preferably be in a range from 20% to 70%.

In one embodiment, if the ratio is less than 20%, the surface area ofthe light emission area PA is exceedingly greater than that of thetransmission area TA, and a user has difficulty viewing images outsidethrough the transmission area TA. In another embodiment, if the ratioexceeds 70%, designing the pixel circuit portion PC, which is to bearranged in the light emission area PA, may be restricted too much.

The first electrode 221 that is electrically connected to the pixelcircuit portion PC is included in the light emission area PA, and thepixel circuit portion PC overlaps with the first electrode 221 so as tobe covered by the first electrode 221. In addition, at least one of theconductive lines, including the scan line S, the data line D, and theVdd line V, described above may be arranged to cross the first electrode221. However, since a ratio at which these conductive lines hindertransmittance is less than that of the pixel circuit portion PC, all ofthe conductive lines may be disposed adjacent to the first electrode 221according to design conditions.

As described above, if the first electrode 221 includes a reflectionlayer formed of a conductive metal on which light may be reflected, thefirst electrode 221 covers the pixel circuit portion PC and reduces orprevents distortion of external images in the light emission area PA dueto the pixel circuit portion PC.

Also, according to the current embodiment of the present invention, asillustrated in FIGS. 3 and 4, the light emission area PA and thetransmission area TA are arranged in the first area R1. The cappinglayer 230 is disposed within the first area R1, and thus, covers boththe light emission area PA and the transmission area TA. In addition,the third electrode 223 is formed in the second area R2 outside thefirst area R1.

In addition, a transmission window may be formed by removing a portionof the second electrode 222 from the transmission area TA, therebyfurther increasing light transmittance of the transmission area TA.Here, the transmission window is not limited to being formed by removinga portion of the second electrode 222 and may also be formed on at leastone of the pixel-defining layer 219, the passivation layer 218, theinterlayer insulating layer 215, the gate insulating layer 213, and thebuffer layer 211.

FIG. 8 is a plan view illustrating an organic light-emitting unitaccording to another embodiment of the present invention.

Referring to FIG. 8, each pixel is formed of red, green, and bluesub-pixels so as to emit white light. However, white light may also begenerated by using colors other than red, green, and blue colors.

In this case, one transmission area TA for each of first electrodes 221a, 221 b, and 221 c of the three sub-pixels is formed. First throughthird data lines D1 through D3 are electrically connected to the firstelectrodes 221 a, 221 b, and 221 c of the three sub-pixels. Also, afirst Vdd line V1 is electrically connected to the first electrodes 221a and 221 b, and a second Vdd line V2 is electrically connected to thefirst electrode 221 c.

In this structure, one large transmission area TA is included for aplurality of sub-pixels, and thus, transmittance of the entire displayapparatus may be further increased and distortion of images due to lightdiffusion may also be further reduced.

Here, one large transmission window may also be formed by removing atleast a portion of a second electrode from the transmission area TA, asdescribed above. The transmission window is not limited to the removedportion of the second electrode but may also be formed on at least oneof a pixel-defining layer, a passivation layer, an interlayer insulatinglayer, a gate insulating layer, and a buffer layer.

A capping layer and a third electrode are also formed in the embodimentof FIG. 8 described above. That is, a capping layer is formed tocorrespond to a transmission area and a light emission area, and thethird electrode is formed around the capping layer. Also, a firstcapping layer is formed in the light emission area, and a second cappinglayer is formed in the transmission area. The light emission area ofFIG. 8 may be regarded as corresponding to areas of the first electrodes221 a, 221 b, and 221 c. The other detailed configuration is the same asthe previous embodiment(s), and thus, description thereof is omitted.

FIG. 9 is a graph showing light transmittance according to thickness ofa capping layer. Referring to FIG. 9, an area A has a largetransmittance, and an area B has a lower light transmittance than thearea A.

As described above, the first capping layer 231 and the second cappinglayer 232 of the capping layer 230 are separately formed.

Visible rays transmit through the transmission area TA, andtransmittance of the second capping layer 232 may preferably be high.However, the second electrode 222 below the second capping layer 232 maypreferably be formed such that a thickness of the second capping layer232 is sufficient to protect the second electrode 222. In more detail,the second capping layer 232 may have a thickness corresponding to thearea A, that is, a range from about 30 Å to about 60 Å.

In the light emission area PA, an image is formed through visible raysgenerated by the intermediate layer 220, and thus, a suitable thicknessof the first capping layer 231 is determined in consideration ofluminance, contrast, and color conversion of visible rays. In moredetail, the first capping layer 231 may have a thickness correspondingto the area B, that is, a range from about 70 Å to about 90 Å.

As a result, the first capping layer 231 is thicker than the secondcapping layer 232.

However, this is an example, and alternatively, the first capping layer231 and the second capping layer 232 may be each formed to have suitablethicknesses. In more detail, considering optical characteristics, theorganic light-emitting display apparatus 2 may suitably vary accordingto the material of the intermediate layer 220, and a suitable thicknessof the first capping layer 231 may vary accordingly. Also, differentmaterials may be determined to form the first capping layer 231 and thesecond capping layer 232, and a range of suitable thicknesses thereofmay also vary.

As described above, a voltage drop of the second electrode 222 isreduced or prevented by using the third electrode 223 to improveelectrical characteristics of the organic light-emitting displayapparatus 2, thereby improving image quality of the organiclight-emitting display apparatus 2.

Also, the second electrode 222 is protected by using the capping layer230 to, e.g., completely prevent deterioration of electricalcharacteristics and image quality of the organic light-emitting displayapparatus 2 due to damage of the second electrode 222.

In particular, the third electrode 223 is easily patterned using thecapping layer 230 to increase manufacturing simplicity and preventdamage of the organic light-emitting device EL when forming the thirdelectrode 223.

Also, the capping layer 230 includes the first capping layer 231 and thesecond capping layer 232, and the first capping layer 231 is formed tocorrespond to the light emission area PA, and the second capping layer232 is formed to correspond to the transmission area TA. Accordingly, asmany visible rays as possible transmit through the transmission area TA,and suitable images are formed in the light emission area PA. Theorganic light-emitting display apparatus 2 suitable for use as atransparent display apparatus having excellent image quality andtransmittance may be easily manufactured.

According to the organic light-emitting display apparatus and the methodof manufacturing the same, electrical characteristics and image qualityof the organic light-emitting display apparatus may be easily improved.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims.

What is claimed is:
 1. A method of manufacturing an organiclight-emitting display apparatus comprising a plurality of pixels eachcomprising a light emission area from which visible rays are emitted anda transmission area through which external light is transmitted, themethod comprising: forming a plurality of pixel circuit portions on asurface of a substrate to respectively correspond to the plurality ofpixels; forming a first electrode in a light emission area of each ofthe plurality of pixels and electrically connected to a correspondingone of the pixel circuit portions; forming an intermediate layer,comprising an organic emissive layer, on the first electrode; forming asecond electrode on the intermediate layer; forming a first cappinglayer on the second electrode corresponding to the light emission area;and forming a second capping layer separate from the first cappinglayer, the second capping layer being formed on the second electrode,spaced from at least a region of the first capping layer in a directionparallel to the surface of the substrate, and corresponding to thetransmission area, wherein the second capping layer comprises aplurality of sub-capping layers, the plurality of sub-capping layerscomprising a first sub-capping layer and a second sub-capping layerarranged adjacent to each other in the direction parallel to the surfaceof the substrate, and wherein a boundary between the first sub-cappinglayer and the second sub-capping layer is in the transmission area. 2.The method of claim 1, wherein the first capping layer and the secondcapping layer are formed using a mask.
 3. The method of claim 1,wherein: the first capping layer is formed in a first area on the secondelectrode and has a first edge, the method further comprises forming athird electrode in a second area other than the first area on the secondelectrode and having a second edge, and a lateral surface of the firstedge of the first capping layer and a lateral surface of the second edgeof the third electrode are formed to contact each other.
 4. The methodof claim 3, wherein the forming of the third electrode comprisespatterning the third electrode by using a pattern of the first andsecond capping layers.
 5. The method of claim 1, wherein the first andsecond sub-capping layers are spaced from each other.
 6. The method ofclaim 1, wherein the first capping layer and the second capping layerhave different thicknesses from each other.
 7. The method of claim 6,wherein the second capping layer is thinner than the first cappinglayer.